vfio/iommu_type1: Remove unused pinned_page_dirty_scope in vfio_iommu

pinned_page_dirty_scope is optimized out by commit 01032156
("vfio/iommu_type1: Mantain a counter for non_pinned_groups"),
but appears again due to some issues during merging branches.
We can safely remove it here.
Signed-off-by: Keqian Zhu <zhukeqian1@huawei.com>
Message-Id: <20210412024415.30676-1-zhukeqian1@huawei.com>
Signed-off-by: Alex Williamson <alex.williamson@redhat.com>

drivers/vfio/vfio_iommu_type1.c

@@ -77,7 +77,6 @@ struct vfio_iommu {
 	bool			v2;
 	bool			nesting;
 	bool			dirty_page_tracking;
-	bool			pinned_page_dirty_scope;
 	bool			container_open;
 };